The economy of Houston is based primarily on the energy industry, particularly oil. However, health care, biomedical research, and aerospace also constitute large sectors. In 2021, the gross domestic product (GDP) of the Houston–The Woodlands–Sugar Land metropolitan statistical area (MSA) was 537 billion, the fourth-largest of any metro area in the United States. The Houston metropolitan area comprises the largest concentration of petrochemical manufacturing in the world, including for synthetic rubber, insecticides, and fertilizers. It is the world's leading center for oilfield equipment construction, with the city of Houston home to more than 3,000 energy-related businesses, including many of the top oil and gas exploration and production firms and petroleum pipeline operators. As of 2011, 23 companies on the Fortune 500 list have their headquarters in, or around, Houston. The Houston–Sugar Land–Baytown metropolitan area ranked 33rd among the nation's 361 MSAs on per capita personal income at US$36,852 - 11.5 percent higher than the national figure of US$33,050. In 2012, Houston was ranked #1 by Forbes for paycheck worth, and, in late May 2013, it was identified as America's top city for job creation. Real estate and corporate location Houston is a major corporate center. The city and surrounding metropolitan region is home to 23 Fortune 500 companies, as well as other multinationals and domestic companies. Of the world's 100 largest non-U.S.-based corporations, more than half have operations in Houston. In 2006, the Houston metropolitan area ranked first in Texas and third in the U.S. within the category of "Best Places for Business and Careers" by Forbes. The 2011 Fortune 500 list shows 23 firms headquartered in the 10-county Houston–Sugar Land–Baytown Metropolitan Statistical Area. Only New York City has more Fortune 500 headquarters within city limits. Finance Banking and financial services are vital to the region. Forty foreign governments maintain trade and commercial offices here and the city has 23 active foreign chambers of commerce and trade associations. Twenty-two foreign banks representing 12 nations operate in Houston and provide financial assistance to the international community. In 1997, Houston had offices of 84 subsidiaries of Japanese companies. Information technology Houston has more than 1,000 computer-related companies. Since its inception in 1999, Houston Technology Center has become the center of technology entrepreneurship in Houston. The center has helped more than 150 emerging technology companies raise more than $400 million in capital and create about 1,000 new jobs. Information technology developed in Houston